Influence Of Pipe Material Research Articles

Influence of pipe materials on in-building disinfection of P. aeruginosa and A. baumannii in simulated hot water plumbing

A framework is needed to account for interactive effects of plumbing materials and disinfectants on opportunistic pathogens (OPs) in building water systems. Here we evaluated free chlorine, monochloramine, chlorine dioxide, and copper-silver ionization (CSI) for controlling Pseudomonas aeruginosa and Acinetobacter baumannii as two representative OPs that colonize hot water plumbing, in tests using polyvinylchloride (PVC), copper-PVC, and iron-PVC convectively-mixed pipe reactors (CMPRs). Pipe materials vulnerable to corrosion (i.e., iron and copper) altered the pH, dissolved oxygen, and disinfectant levels in a manner that influenced growth trends of the two OPs and total bacteria. P. aeruginosa grew well in PVC CMPRs, poorly in iron-PVC CMPRs, and was best controlled by CSI disinfection, whereas A. baumannii showed the opposite trend for pipe material and was better controlled by chlorine and chlorine dioxide. Various scenarios were identified in which pipe material and disinfectant can interact to either hinder or accelerate growth of OPs, illustrating the difficulties of controlling OPs in portions of plumbing systems experiencing warm, stagnant water.

Influence of pipe materials on the microbial community in unchlorinated drinking water and biofilm

Biodegradable compounds can cause undesired microbial growth in drinking water systems and these compounds can originate from the water or pipe materials used in drinking water systems. The aim of our study was to determine the influence of different pipe materials on the microbial populations in water and biofilm under semi-stagnant conditions. The microbial communities in biofilm and water, which were in contact with seven different materials, were characterized by determining ATP concentrations, microbial composition gene copy numbers of some specific microbial groups. The ATP concentration in water and biofilm varied between the different materials with glass (negative control) < copper < PVCC < PE-Xc < PE-Xb < PE-100 < PVC-P. Gene copy numbers of Legionella spp., Mycobacterium spp., Pseudomonas spp., Aeromonas spp., fungi and Vermamoeba vermiformis were also higher for PVC-P and PE than for glass, copper and PVCC. The bacterial community composition in water and biofilm varied between materials as well. PERMANOVA and CAP analysis demonstrated that copper and PVC-P are different when compared to the other materials. Furthermore, bacterial community composition and ATP concentrations in water and biofilm were similar after eight and 16 weeks incubation, but differed from results obtained after one week. Finally, the ATP, the specific microbial groups and the bacterial community composition also differed between water and biofilm on each material. We conclude from our study that pipe material is an important factor that influences the biomass concentration, abundance of specific microorganisms and the bacterial community composition in distribution systems with unchlorinated drinking water.

Influence of pipe material on biofilm microbial communities found in drinking water supply system

The biofilms and water samples from a model installation built of PVC-U, PE-HD and cast iron pipes were investigated using standard heterotrophic plate count and 16S rRNA Next Generation Sequencing. The results of the high throughput identification imply that the construction material strongly influences the microbiome composition. PVC-U and PE-HD pipes were dominated with Proteobacteria (54–60%) while the cast pipe was overgrown by Nitrospirae (64%). It was deduced that the plastic pipes create a more convenient environment for the potentially pathogenic taxa than the cast iron. The 7-year old biofilms were described as complex habitats with sharp oxidation-reduction gradients, where co-existence of methanogenic and methanotrophic microbiota takes place. Furthermore, it was found that the drinking water distribution systems (DWDS) are a useful tool for studying the ecology of rare bacterial phyla. New ecophysiological aspects were described for Aquihabitans, Thermogutta and Vampirovibrio. The discrepancy between identity of HPC-derived bacteria and NGS-revealed composition of biofilm and water microbiomes point to the need of introducing new diagnostical protocols to enable proper assessment of the drinking water safety, especially in DWDSs operating without disinfection.

Semi-volatile organic compounds in tap water from Hangzhou, China: Influence of pipe material and implication for human exposure

Investigations on environmental behaviors of SVOCs have recently received great attention. However, the SVOC occurrence and influence of pipe materials on SVOC levels in the tap water have received little attention. Herein, we collected tap water samples from 25 households constructed at different ages in Hangzhou, China. Concentrations of 61 SVOCs, including phthalate esters (PAEs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs), were simultaneously determined in these collected samples. The potential human exposure risks were evaluated via the hazard index calculation. Our results showed that the total concentration of detected SVOCs (∑SVOCs) ranged from 110 to 289 μg/L (mean, 179 μg/L), and the SVOCs were dominated by PAHs (mean, 116 ng/L) and PAEs (mean, 55 ng/L) in Hangzhou tap water. 12 PCB congeners were detected in Hangzhou tap water samples, with hepta-CBs (68% of samples) as the most frequently detected PCBs. Nearly all tap water samples contained measurable o, p’-DDE, p, p’-DDT, and p, p’-DDD, and ∑DDTs had significantly (p < 0.05) higher concentrations than ∑HCHs. All target PAHs had high detection frequencies (>72%) in tap water samples, with their mean concentrations in the range of 2.1–41 ng/L. Tap water from steel pipes had relatively lower SVOC concentrations than that from either reinforced concrete, gray cast iron, or ductile iron pipes. Although no carcinogenic risks originating from exposure to SVOCs through ingestion and bathing were observed, the tap water from steel pipes showed relatively low exposure risks than that from other materials. Data provided here, for the first, are helpful in understanding the influence of pipe materials on human SVOC exposure risks through tap water intake.

Effect of pipe materials on chlorine decay, trihalomethanes formation, and bacterial communities in pilot-scale water distribution systems

In this study, the influence of pipe materials on chlorine decay, trihalomethanes formation, as well as on microbial community composition of the biofilms formed on the pipe walls in a model full-scale water distribution system was investigated. The chlorine decay experiment showed that the turbulent flow model fitted the experiment data of chlorine decay well, with stainless steel pipe that had the highest rate constant of chlorine decay, and followed by ductile iron pipe and polyethylene pipe. Meanwhile, the formation of trihalomethanes under the three different pipe materials followed the order as: polyethylene pipe > ductile iron pipe > stainless steel pipe. Microbial community analysis showed that biofilm from polyethylene pipe had much higher diversity than that from the ductile iron pipe and stainless steel pipe. In addition, clear differences in the bacterial community structure among biofilms of different pipe materials were observed. The ductile iron pipe biofilm was mainly composed of Enhydrobacter (33.84%), Propionibacterium (8.08%) and Acinetobacter (5.59%). The polyethylene pipe biofilm contained Sphingomonas (25.25%), Streptococcus (7.64%), Ralstonia (4.83%), Pseudomonas (4.63%), and Escherichia–Shigella (4.71%). The stainless steel pipe biofilm was abundant with Flavobacterium (24.76%), Arcicella (12.03%), and Acidovorax (8.98%). Moreover, the occurrence of opportunistic pathogens was detected, especially in the biofilm of polyethylene pipe, followed by ductile iron pipe and stainless steel pipe. The integrated findings in this study suggest that ductile iron pipe and stainless steel pipe are more suitable as plumbing material than polyethylene pipe in drinking water distribution systems.

Streaming electrification of mineral insulating oil and synthetic ester MIDEL 7131

Determining the Electrostatic Charging Tendency (ECT) level of insulating liquids requires no large and therefore costly transformers or modelling systems. Small laboratory systems are characterised by simple design and methodology, low volume of liquid sample required for testing, low cost of construction and the following tests. This also applies to pipe flow systems. This paper presents comparative studies of the phenomenon of streaming electrification of mineral TRAFO EN insulating oil and MIDEL 7131 synthetic ester flowing through a pipe made of conventional cellulose paper and modern aramid paper. Electrification current vs. liquid flow speed was measured. The influence of pipe material was determined. Also the effect of temperature and sample aging time on the extent of the streaming electrification was studied. With the Abedian-Sonin model, volume density of the qw charge, which is a parameter describing ECT of insulating liquids, was determined.

Effects of pipe materials on chlorine-resistant biofilm formation under long-term high chlorine level.

Drinking water distribution systems are composed of various pipe materials and may harbor biofilms even in the continuous presence of disinfectants. Biofilms formation on five pipe materials (copper (Cu), polyethylene (PE), stainless steel (STS), cast iron (CI), and concrete-coated polycarbonate (CP)) within drinking water containing 1.20mg/L free chlorine, was investigated by flow cytometry, heterotrophic plate counts, and denaturing gradient gel electrophoresis analysis. Results showed that the biofilms formation varied in pipe materials. The biofilm formed on CP initially emerged the highest biomass in 12days, but CI presented the significantly highest biomass after 28days, and Cu showed the lowest bacterial numbers before 120days, while STS expressed the lowest bacterial numbers after 159days. In the biofilm community structure, Moraxella osloensis and Sphingomonas sp. were observed in all the pipe materials while Bacillus sp. was detected except in the CP pipe and Stenotrophomonas maltophila was found from three pipe materials (Cu, PE, and STS). Other bacteria were only found from one or two pipe materials. It is noteworthy that there are 11 opportunistic pathogens in the 17 classified bacterial strains. This research has afforded crucial information regarding the influence of pipe materials on chlorine-resistant biofilm formation.

Influence of pipe material and surfaces on sulfide related odor and corrosion in sewers

Hydrogen sulfide oxidation on sewer pipe surfaces was investigated in a pilot scale experimental setup. The experiments were aimed at replicating conditions in a gravity sewer located immediately downstream of a force main where sulfide related concrete corrosion and odor is often observed. During the experiments, hydrogen sulfide gas was injected intermittently into the headspace of partially filled concrete and plastic (PVC and HDPE) sewer pipes in concentrations of approximately 1000 ppm v. Between each injection, the hydrogen sulfide concentration was monitored while it decreased because of adsorption and subsequent oxidation on the pipe surfaces. The experiments showed that the rate of hydrogen sulfide oxidation was approximately two orders of magnitude faster on the concrete pipe surfaces than on the plastic pipe surfaces. Removal of the layer of reaction (corrosion) products from the concrete pipes was found to reduce the rate of hydrogen sulfide oxidation significantly. However, the rate of sulfide oxidation was restored to its background level within 10–20 days. A similar treatment had no observable effect on hydrogen sulfide removal in the plastic pipe reactors. The experimental results were used to model hydrogen sulfide oxidation under field conditions. This showed that the gas-phase hydrogen sulfide concentration in concrete sewers would typically amount to a few percent of the equilibrium concentration calculated from Henry's law. In the plastic pipe sewers, significantly higher concentrations were predicted because of the slower adsorption and oxidation kinetics on such surfaces.